Generating gimple code with gimple_build_assign

[Richard Biener]

On Mon, Apr 6, 2015 at 7:29 PM, Steve Ellcey <sellcey@imgtec.com> wrote:
> I have a simple gimple question.  I am trying to introduce an array
> into a gimple stream and create a pointer to that array.
>
> I can create the array with:
>
>         array_type = build_array_type_nelts (char_type_node, 256);
>         array_var = create_tmp_var (array_type, "spill");
>
> I can create a pointer to an array with:
>
>         ptr_type = build_pointer_type (array_type);
>         ptr_var = create_tmp_var (ptr_type, "spill");
>
> But if I try to create an assignment to get the pointer to point to
> the array I get a verify_gimple error.
>
> I have tried:
>
>         stmt = gimple_build_assign (ptr_var, array_var);
> and
>         stmt = gimple_build_assign (ptr_var, ADDR_EXPR, array_var);
>
> but neither of those work.  I also tried making the pointer be a
> pointer to char instead of a pointer to array of char but that didn't
> seem to work either.  Can someone help me with the magic formula to
> generate gimple code that causes ptr_var to point to array_var?
> Is ADDR_EXPR the right way to get the address of the array instead of
> the value in a gimple_build_assign call?

ADDR_EXPR is one of the "single-rhs" tree codes so you need to build
a GENERIC expression here:

  stmt = gimple_build_assing (ptr_var, build_fold_addr_expr (array_var));

Richard.

>
> Steve Ellcey
> sellcey@imgtec.com